CCC 1325 “The Eucharist is the efficacious sign and sublime cause of that communion in the divine life and that unity of the People of God by which the Church is kept in being. It is the culmination both of God’s action sanctifying the world in Christ and of the worship men offer to Christ and through him to the Father in the Holy Spirit.”1
1 Congregation of Rites, instruction, Eucharisticum mysterium, 6.